Ten years ago, Zong Yue was betrayed, and forced to escape and hide, and his loyal servant was skinned alive. The guard that resulted in all of these "accidentally" died because of a snake's bite. One of his children was raised by an old widow. After the child grew up, he entered the palace as a eunuch to make ends meet.
Because of this background, the department in charge of manpower did not doubt him and let him enter, despite having a reputation of being very strict with background checks. Afterward, because of his loyalty and shrewdness, he was even chosen to serve beside the Emperor.